Eraser cleaner



Dec. 29, 1942.

F. M. SCHAE'FER ERASER CLEANER Filed Feb. 11, '1941 2 Sheets-Sheet 1 Dec. 29, 1942. M. SCHAEFER Y ERASER CLEANER Filed Feb. 11, 1941 2 Sheets-Sheet 2 "ii/117761777225 iiii'iiilfii'r?) rm 4 9/AZ7 M Z. 0% w h Patented Dec. 29, 1942 men ERASER CLEANER Frank M. Schaefer, Chicago,

111., assignor to E. W. A. Rowles Company, Arlington Heights, 111., a; corporation of Illinois- Application February 11, 1941, Serial No. 378,429

3 Claims.

This invention relates to machines for cleaning chalk and dust from erasers and confining the same against free escape into the air.

An object of this invention is to provide an improved machine for cleaning erasers.

Another object of this. invention is to provide an eraser cleaning machine which is of simple and compact design, efli cient in operation and of rugged but light construction. so as to be readily carried about for use.

A feature of this invention is found in the provision of a machine for cleaning A erasers which is inexpensive in cost and adaptedto both clean erasers and to remove chalk dust from the trough or like usually provided about blackboards.

Further objects, features and advantages of this invention will become apparent from the following description when taken in connection with the accompanying drawings in which:

Fig. 1 is a side view of one form of the invention with parts thereof shown in section;

Fig. 2 is a sectional View taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary detailed view showing the assembly of the heaters used in the rotary cleaning device shown in the cleaning machine of Figs. 1 and 2;

Fig. 4 is a View in perspective of another form of the invention;

Fig. 5 is a longitudinal sectional view of the cleaning machine shown in Fig. 4;

Fig. 6 is a sectional view taken along the line 8-6 in Fig. 5;

Fig. '7 is a fragmentary sectional View taken along the line l-l in Fig. 6; and

Fig. 8 is a covering means for closing certain of the air inlet passages in the machine shown in Fig. 4, when such machine is being operated to remove chalk and dust from a blackboard trough.

The eraser cleaning machine of this invention includes a rotary cleaning device operatively associated with a suction fan, with the cleaning device and the fan being in operative engagement with a common motor. All three of these elements are enclosed; within a housing structure of streamlined contour having an air inlet and an air outlet and means for guiding an eraser to be cleaned across the air inlet. The rotary cleaning device is comprised of both beaters and brushes and is arranged at the air inlet in a manner to operate on the erasers being moved across the air inlet. All of the dust removed from the erasers by the cleaning device driven engagement with the motor.

is carried by the suction fan intoa dust bag which is connected to the air outlet. The invention contemplates further means for closing the air inlet normally used for the cleaning of erasers and opening a supplementary inlet and attaching to such supplementary inlet a hose or conduit attachment adapted to be moved about to pick up dust or dirt from the usual blackboard trough. The machine is entirely portable and of a construction such that it may be easily carried from room to room of a school building, and when using the blackboard cleaning attachment may be easily carried with one hand while the attachment is manipulated with the other.

Referring to the drawings, there is shown in Fig. 1 an eraser cleaning machine which is comprised of a standard or frame member I!) having a base portion H at its lower end. provided with legs [2 for standing the machine in an upright operating position and a handle portion H3 at its upper end for carrying the machine around. Intermediate the base portion H and handle portion I3 is a cavity or chamber I i open at both ends, a housing member l6 for a rotary cleaning device ll being connected to the member H) at one end of the cavity M and a housing member [8 for an operating motor (not shown) being connected to the member H1 at the other end of the cavity M. The motor is separated from the chamber 14 by a partition or separating plate I9 which extends transversely across the inner end of the housing member I3, the outer end of the housing l8 being closed. A projecting end portion 2| of the motor shaft is rotatable in the partition plate i9 and extends therethrough completely across the chamber M and the cleaning chamber 22 within the housing element It, the chambers M and 22' beingopen to each other. The free end 23 of the shaft portion 2! is rotatably supported in a bearing member 24* mounted in a boss portion 26 formed at the closed end 21 of the housing member l5. An air fan 28' is suitably mounted about the shaft portion 2i and within the cavity M, the cleaning device I"! being also mounted on the shaft portion 21 but axially displaced from the fan 28 for location in the chamber 22-. From the above description and consideration of Fig. 1, it is seen that the chambers 22, I4, and the chamber for the motor are arranged longitudinally of the machine housing structure designated generally as 29, with the fan 28, and cleaning. device ll being mounted on the motor shaft in. direct Although the housing structure 29 is illustrated as being formed of three component parts it is to beunderstood that it may be modified to include a lesser number of parts Without in any manner affecting the improved arrangement and assembly of the machine operating elements.

The housing member I6 is integrally formed at the top thereof with a track portion 3| which extends transversely of the cleaning machine and parallel to the handle portion l3 (Fig. 2). The track portion 3| is of substantially trough shape section and is extended equally on opposite sides of the housing member l6 with each extension being of a length to conveniently support an eraser 32 thereon. An air inlet 33 which opens into the cleaning chamber 22 is formed in the bottom 42 of the track portion 3| about centrally of the track ends. As an eraser 32;therefore, is moved along the track portion 3|;Vit is guided by such portion for passage across the opening 33. The cleaning device I! within the cleaning chamber 22 is arranged transversely of the track means 3| and across the opening 33 in a manner such that the device rotates in a direction longitudinally of the eraser 32 which tioned between certain of the brushes 3'! are centrifugally actuated wire beaters 38. The outer ends of the beaters 38 are 'of hooked'shape and are positioned in the circumference of the brushes 3?. The inner ends of the beaters 38 are of substantially eyelet shape for pivotal connection to a rod 39 which is positioned axially of the hub portion 34 and mounted in the annular flange portions 36. As is shown in Fig; 3 each rod 39 is formed with axially spaced annular grooves 4| which are adapted to receive therein the eyelet portions of the beaters 38. In the arrangement of the cleaning device I! relative to the opening 33 it is contemplated that the bottom 42 of the track portion 3| be substantially tangent to the circumference of the r cleaner so that the eraser 32 in passing over the cleaning device is operated on by a brushing or sweeping action. Where the cleaning device projects an appreciable amount through the opening 33 and above the bottom 42 of the track portion, it tends to scrape and pull the bottom of the eraser 32, so as to appreciably shorten the service life thereof.

In the operation of the machine shown in Figs. 1 and 2 the extension cord 43 is plugged into a convenient electrical outlet and the motor for operating the fan 28 and the cleaner I! is turned on by the switch 44, which is mounted in the motor housing I8. It is contemplated that the cleaner I! be rotated in a clockwise direction. as viewed in Fig. 8, and that the eraser 32 be slid along the track portion 3| in a direction from right to left, as also viewed in Fig. 2, so as to be moved into the direction of rotation of the cleaner As the eraser moves across the rotary cleaner it is alternately engaged by the heaters 38 and a series of brushes 31, the beaters providing a rubbing or sliding impact on the eraser to loosen the dust therefrom and the brushes 3! functioning to sweep this loosened dust away from the eraser. The dust which is thus removed is carried through the chambers 22 and 4 by the action of the fan 28 and is discharged from the chamber i4 through an opening or outlet 43 formed therein. A dust bag 41 of a type usual in vacuum cleaners is suitably connected to the outlet 46 for catching and collecting the dust.

As the eraser 32 is moved along the track portion 3| a position is reached such that the inlet 33 is completely covered and closed by the eraser. This closing of the inlet 33 not only reduces the efficiency of the fan 28 in removing the chalk dust from the chambers 22 and [4, but also increases the load on the operating motor by virtue of the fan 28 operating against the closed chamber 22. In order to continuously discharge from the machine the chalk dust which is being removed from the erasers and to eliminate any overloading of the operating motor, "air passages 48 and'48A opening into the chamber 22 are formed in the track portion'3l at a point below the inlet 33. When the inlet 33, therefore, is closed by the positioning of an'eraser thereover. air is by-passed about the opening 33 and into the chamber 22 through the passages 48 and 48A. A continuous flow of air is thus maintained through the chambers l4 and 22 at all times during the cleaning operation so that the motor always operates with a substantially constant load. It is apparent. of course, that prior to the closing of the inlet 33 some air will pass through the passages 48 and 48A as well as through the inlet 33. However, the air passing through these passages at such times does not interfere in any way with the efiicient operation of-the rotary cleaner l1 and the suction fan 28. i

In the machine illustrated in Figs. 4 to 8, the

housing means or structure 29' is similar in all respects to the housing structure 29 previously described in connection with the machine inFigs. 1 and 2, except for the telescopic engagementof the cleaner housing l6 with the frame member Hi. The telescopic engagement of both the cleaner housing l6 and the motor housing I8 with the frame member ID provides for an improved alignment of these housing members and for a more rigid construction of the housing structure. The track portion 3| and air inlet or cleaning opening 33 of the housing member I6, however, are similar in all respects to the same parts in Figs. 1 and 2. also for the pur ose of reducing the overall weight of the machine the base portion II of frame member ID is cut away between the legs l2, as is clearly shown in Fig. 4.

The motor (not shown) for operating the air fan 49 and rotary cleaner 5| (Fig. 5) includes a motor shaft having an end portion 52 which extends through the partition plate I3 into the fan chamber M. The shaft portion 52 is threaded over a portion of its length for threaded engagement with an inner fan hub 53 which has a correspondingly threaded inner bore. It is contemplated that the outer fan hub 55, fan blades 85, and fan back plate 6| be integrally formed by die-casting. The hub 53 may be provided in steel or like metal and is formed with annularly extending portions 86 and 81 near one end thereof. The portion 81 is positioned between the back plate 5| and a circular disc or plate 88 formed of sheet metal and spot-welded or otherwise secured to a bracing plate 89 mounted on the back plate 6| by rivets '99. The discs 88- and 89 and the hub 53 may be preassembled prior to their assembly to the remaining die cast fan portion. On riveting of the disc member 89 to theback plate 6|, therefore, there is provided a fan assembly of rugged and integral construction. By Virtue of the steel hub portion 53 there is assured a positive threading with the shaft portion 52 to mount the fan 49.

The partition member I9 near its center part is formed on one side with a pressed out portion corresponding in shape to a cup member 92 secured by screws 93 to the opposite side of the partition member l9. The portions 9| and 92 provide a housing for a bearing unit having a bearing portion 94 and spacer means includinga felt washer 95, a steel washer 91 and a retaining ring 58. The shaft portion 52 is J'ournaled directly in the bearing portion. 9 5 whilethe steel washer and plate portion 9| are engageable with the hub portion 53 of the fan 54,'the annular shoulder 86 defining the position of the hub portion 53 Within the bearing unit. Since the opposite end of the motor shaft (not shown) is rotatably supported in the housing portion l8, the bearing unit eliminates any necessity for an accurate aligning of the shaft bearings thus eliminating assembly difficulties and correspondingly reducing manufacturing costs. Any misalignment in the shaft bearings, therefore, is compensated for-by" the bearing unit without impairing the service life or operating efliciency of themachine. It is contemplated further that the fan assembly 55 be threadable on the motor shaft 52 in the direction of rotation of the motor to assure its being tightly held on the shaft at all. times.

A fan. 99 for cooling the motor is formed with a: cup-shaped hub portion I59 corresponding in form to the cup-shaped member 92 and fitting in part over such latter member, the fan 99 being suitably mounted on the shaft end 52 for concurrent rotation therewith. It is thus seen that the assembly of the fan 49, the motor fan 99 and the bearing for the motor shaft is simply and compactly arranged in a minimum of space. This assembly includes further the rotary cleaner 5| which is mounted on and threadably engaged with the outer hub portion 55 of the fan 49.

The rotary cleaning device 5| (Figs. 5 and. 6) is comprised of a tubular hub or body portion. 56 having angularly arranged radially extending flange portions 51 thereon axially spaced apart a distance substantially equal to the width of the cleaning opening 33-. The hub portion 55 is formed with an extension 58 which projects into the impeller chamber l4, such extension being internally threaded for threadedengagement with the outer fan hub 55. By virtue of this conwire 64- which is weaved about thebrushes and through the apertures in a manner clearly illustrated in Fig. 5. Each pin or rod 39 for supporting the beaters 38 is mounted in a pair of corresponding flange portions 51 for arrangement between certain of the brushes 63 the relation of the heaters 38' and brushes 63 in the device 5| being similar to the brush and beater arrangement of the cleaner IT. in the machine of' Figs. 1 and 2. I

As shown'in Figs. 6 and 7 the bottom 52" of the track portion 3| is built up with shims or plate members 65, the number and thickness of the plates depending upon the particular operating conditions fort'he machine. The plates 65 are secured to the track 3| by screws 51 which are seated beneath the surface of the uppermost plate 66 so as notto interfere with the passage of an eraser 32 thereon. In the initial assembly of the machine, therefore, the cleaning device 5| is arranged so that the uppermost plate 55 is tangent'to the brush circumference. During the us of the machine the brushes 63 become worn so that in time the efficiency of their cleaning 1 action on the eraser is appreciably reduced. It is contemplated, therefore, that the plates 55 be separately removable from the track bottom 42 in accordance with the wear of the brushes 63 so that asubstantially tangential relation of the bottom of the track with the circumference of the brush is maintained at all times. In this manner an efiicient and positive operation of the brushes is. assured over the entire service life of the machine. Since the plates 55 may be provided in a relatively cheap material, it is apparent that this construction appreciably reduces the servicing costs of the machine by prolonging the active life of the. rotary cleaner 5| and hence eliminat ing frequent replacements thereof.

With the rotary cleaner 5| and the upper one of the plates 55 in their relative tangential arrangement, the operation of the machine of Fig. 4 is similar in all respects to the operation of the machine in Fig. 1, so that a description of such operation is believed to be unnecessary. During this operation, however, it sometimes ocours that chalk dust is discharged through the supplementary air passage 48A which is positioned in the track portion 3| in the direction of rotation of the cleaner 5|. With the cleaner rotating in a clockwise direction, as viewed in Fig.

struction and assembly of the motor, fan 49, and

rotary cleaning device 5|, the fan and cleaning device are in direct driven engagement with the motor while being positioned in their respective chambers. In the practice of thisinvention itis contemplated that the hub extension 58 of the rotary cleaner 5| be of a length such that on engagement of the-extension end 59 with the fan back plate 6| the'flange portions 51 will be disposed on opposite sides of the opening 33, thus positioning the cleaner in anoperating position relative to the opening. The hub portion 56 be tween the flange portions 51 is formed with a series of longitudinally aligned apertures 62, each of which is adapted to receive therein a brush 53. The brushes 63 for each axial row are retained in their corresponding apertures 62 by a 6,. this passage is seen to be the one located atv the right end of the track portion 3|, as also viewed in Fig. 6. To eliminate this undesirable discharge of dust a flap valve 58 is positioned over the inner end of the passage 58A but clear of the travel ofthe cleaner 5|. The valve 58 includes a supporting pin 69 which is suitably mounted in therib or brace portions H of the housing member 16'. Assembly of the pin 59 in the portions H is facilitated by its insertion into an assembled position through the aperture provided in the-housing member I6 for the connecting screw 12. Positioning of the valve transversely of the passage 48A is accomplished by supporting the flap or ear portions I3 about the reduced pin sections M. Since the valve 58 is freely rotatable on the pin 59 it is entirely responsive to the difference in the velocity pressures in the passage 48A and chamber 22' to open and close the passage 48A. The closed position of the valve 58 is determined by a shoulder it formed at the bottom of the passage and in the rib portions 1 When the machine of Fig. 4 is operated for cleaning erasers, the flow of air in the chambers sages 48 and 48A and air outlet 46. During this operation a supplementary or second air inlet 11 formed in the closed end 13 of the housing member I6 is closed by a cover plate or cap 19. Positioning of the inlet H in the housing end 18 is provided by virtue of the bearing support of the motor shaft in the plate l9, thus leaving the housing end 18 entirely free of any bearing means for the shaft. nection with a suitable hose attachment (not shown) which may be manually manipulated to lift or remove chalk dust from around a blackboard and particularly from the blackboard trough. In the operation of the machine in this manner it is desirable, of course, that the greatest suction effect of the fan 49 be at the inlet Tl. It is necessary, therefore, that at such times the inlet 33 and passages 58 and 48A be closed, so that the flow of air in the chambers 22' and I4 is entirely through the secondary air inlet 11. This is accomplished by covering means 8| (Fig. 8) which includes a pair of U-shaped clamps or clips 82 connected together by an elastic band 83. The band 83 is of a width to fit transversely across the bottom 42 of the track portion 3|, while a clamp 82 is adapted to fit about each end of the track portion to cover a corresponding passage 48 and 48A. The covering means 8! is retained in position over the inlet 33 and passages 48 and 48A by virtue of the tension in the elastic band 83. With the passages 48 and 48A and opening 33 thus closed it is clear that the fan 49 can draw air into the chamber 22' onlythrough the air inlet 11 and its associated hose attachment. In the cleaning of a blackboard trough. therefore, the machine is carried in one hand by the handle portion l3 while the hose attachment is manipulated with the other. Because of the tangential relation between the rotary cleaning device and the bottom 42 of the track portion 3!. the brushes 63 and heaters 38 do not in any way interfere with the closing of the air inlet 33 by the band member 83. When the machine is to be operated for cleaning erasers, it is only necessarv to remove the covering means 8| and to replace the cap member 19 over the air inlet TI.

The invention thus provides a machine for cleaning erasers which is simple and compact in construction. effic ent in operation, and assembled in a manner to provide a streamlined contour of pleasing ap earance. The machine is very inexpensive in cost and is thus commercially ava lable to any sc ool hav ng a source of electricity. Althou h t e cleanin mach ne is ada ted to both clean erasers and chalk dust from around t e black oard. it is nevertheless very l ght in we ght and may be easily carried about in one hand.

The present invention has been described and illustra ed w th refe ence to seve al preferred forms thereof. but it is to be understood that (t an es there n can be made w ich are w thin the full intended sco e of this invention as defined by the a pended claims.

I claim:

1. In a machine for clean ng erasers includ ng otary clean n means and fan means operativelv a soc ated with said rota y clean ng means. the combinat on of means for housing said two means. sa d housin means hav ng an air chamber therein with an inlet and an integrally formed track portion for guiding erasers across said in The inlet 11 is adapted for con- 22' and I4 is through the airinlet 33and pas-- let, said rotary cleaning means being positioned at said inlet to remove the dust from the erasers moved across said inlet, with said erasers being of a length to extend entirely across the inlet to close the same, said chamber having an air outlet positioned relative to said fan means so thatthe dust removed from said erasers by said rotary cleaning means is discharged therethrough from said housing means, and means for bypassing the air about. said air inlet when said inlet is closed by an eraser so that the dust is continuously discharged from said machine regardless of the position of an eraser relative to said inlet, said latter means including an air passage in said housing means connecting said air chamber with the atmosphere.

2. In a machine for cleaning an eraser having rotary cleaning means, suction means operatively associated with said cleaning means, and a driving motor common to said two means, the combination-of housing means for .said three defined elements having a cleaning chamber and a suction chamber, said cleaning means being located in said cleaning chamber and said suction means being located in said suction chamber, with said two chambers being open to each other, said housing means having an inlet opening therein at said cleaning chamber and an outlet opening therein at said suction chamber, with said suction means operating to provide a flow of air in said two chambers through said two.openings, and track means at said inlet opening for guiding an eraser to be cleaned across the same, said cleaning means being positioned at said inlet opening to operate on said eraser to remove the dust therefrom, with the dust from said eraser being carried .by said air flow and discharged from said'machine through said outlet opening, said eraser during its movement along said track means extending across said inlet opening to stop the, flow of air into said cleaning chamber, so that the load on said motor produced by said suction means. is greatly increased, and by-pass means including an air passage in said track portion connecting said cleaning chamber with the atmosphere for admitting air into'said cleaning chamber when said inlet opening is closed to prevent said motor from becoming overloaded. ,3. In a machine for cleaning erasers having rotary cleaning means and suction means arranged in a cooperating relation with said cleaning means, the combination of means for housing said two means including a chamber for said r0- tary cleaning means, said housing means having an air inlet and an air outlet in operative association with said suction means and a passage adapted to by-pass air about said inlet, means for guiding an eraser to be cleaned across said air inlet, means rotatably supporting said cleaning means at said inlet for operation on said eraser, with the dust removed from said eraser by said cleaning means being discharged through said outlet, said eraser during its movement across said inlet closing the same and effecting a change of air pressure in said chamber, and valve means in said air passage operable in response to the air pressure in said chamber and arranged to close said passage when said inlet is open, and to open said passage when said inlet is closed by an eraser to provide for a substantially continuous discharge of dust from said outlet.

FRANK M. SCHAEFER. 

